Methods and systems for automatically identifying a logical circuit failure in a data network

ABSTRACT

A disclosed example method to identify a failure in a logical circuit involves receiving non-requested trap data from a plurality of switches forming a logical circuit. The logical circuit spans first, second, and third logical networks. The example method also involves polling first and second switches of the logical circuit exclusive of others of the plurality of switches of the logical circuit. The first switch forms a first network-to-network interface between the first logical network and the second logical network. The second switch forms a second network-to-network interface between the second logical network and the third logical network. The first and second switches are selected for polling based on the trap data indicating a problem at the first and second switches. The example method also involves identifying a failure of the logical circuit without manual intervention based on the polling.

PRIORITY APPLICATION

This patent arises from a continuation of U.S. patent application Ser.No. 10/745,170, filed Dec. 23, 2003, now U.S. Pat. No. 8,203,933, whichis hereby incorporated herein by reference in its entirety.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to U.S. patent application Ser. No.10/348,077, entitled “Method and System for Obtaining LogicalPerformance Data for a Circuit in a Data Network,” filed on Jan. 21,2003, and U.S. patent application Ser. No. 10/348,592, entitled “Methodand System for Provisioning and Maintaining a Circuit in a DataNetwork,” filed on Jan. 21, 2003. This application is also related toand filed concurrently with U.S. patent application Ser. No. 10/745,117,entitled “Method And System For Providing A Failover Circuit ForRerouting Logical Circuit Data In A Data Network,” filed on Dec. 23,2003, U.S. patent application Ser. No. 10/744,281, entitled “Method AndSystem For Utilizing A Logical Failover Circuit For Rerouting DataBetween Data Networks,” filed on Dec. 23, 2003, U.S. patent applicationSer. No. 10/745,047, entitled “Method And System For AutomaticallyRenaming Logical Circuit Identifiers For Rerouted Logical Circuits In AData Network,” filed on Dec. 23, 2003, U.S. patent application Ser. No.10/744,921, entitled “Method And System For Automatically ReroutingLogical Circuit Data In A Data Network,” filed on Dec. 23, 2003, U.S.patent application Ser. No. 10/745,168, entitled “Method And System ForAutomatically Rerouting Logical Circuit Data In A Virtual PrivateNetwork,” filed on Dec. 23, 2003, U.S. patent application Ser. No.10/745,116, entitled “Method And System For Automatically Rerouting DataFrom An Overbalanced Logical Circuit In A Data Network,” filed on Dec.23, 2003, U.S. patent application Ser. No. 10/744,283, entitled “MethodAnd System For Real Time Simultaneous Monitoring Of Logical Circuits InA Data Network,” filed on Dec. 23, 2003, U.S. patent application Ser.No. 10/744,555, entitled “Method And System For Prioritized Rerouting OfLogical Circuit Data In A Data Network,” filed on Dec. 23, 2003. All ofthe above-referenced applications are assigned to the same assignee asthe present application and are expressly incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates to the routing of data using logicalcircuits in a data network. More particularly, the present invention isrelated to automatically identifying a failure in a logical circuit in adata network.

BACKGROUND

Data networks contain various network devices, such as switches, forsending and receiving data between two locations. For example, framerelay and Asynchronous Transfer Mode (“ATM”) networks containinterconnected network devices that allow data packets or cells to bechanneled over a circuit through the network from a host device to aremote device. For a given network circuit, the data from a hostlocation is delivered to the network through a physical circuit such asa T1 line that links to a switch of the network. The remote device thatcommunicates with the host through the network also has a physicalcircuit to a switch of the network. The communication path between theswitches associated with the host and the remote device that passesthrough the network is a logical circuit.

In frame relay and ATM networks, end devices do not select differentroutes for data packets or cells sent between the host and the remotelocation, but always send the data packets or cells through the samepath. A host device may have many logical circuits, such as permanentvirtual circuits (“PVCs”) or switched virtual circuits (“SVCs”), linkedto many remote locations. For example, a PVC sends and receives datapackets or cells through the same path leading to the switch of theremote device's physical connection.

In large-scale networks, the host and remote end devices of a networkcircuit may be connected across different local access and transportareas (“LATAs”) which may in turn be connected to one or moreInter-Exchange Carriers (“IEC”) for transporting data between the LATAs.These connections are made through physical trunk circuits utilizingfixed logical connections known as Network-to-Network Interfaces(“NNIs”).

Periodically, failures may occur to the trunk circuits or the NNIs ofnetwork circuits in large-scale networks causing lost data. Currently,such network circuit failures are handled by dispatching technicians oneach end of the network circuit (i.e., in each LATA) in response to areported failure. The technicians manually access a logical elementmodule to troubleshoot the logical circuit portion of the networkcircuit. The logical element module communicates with the switches inthe data network and provides the technician with the status of thelogical connections which make up the logical circuit. Once thetechnician determines the status of a logical connection at one end of alogical circuit (e.g., the host end), the technician then must access anetwork database to determine the location of the other end of thelogical circuit so that its status may also be ascertained. If thetechnician determines the logical circuit is operating properly, thetechnician then accesses a physical element module to troubleshoot thephysical circuit portion of the network circuit to determine the causeof the failure and then repair it.

Current methods of determining network circuit failures, however, sufferfrom several drawbacks. One drawback is that troubleshooting the logicaland physical circuits is time consuming and results in dropped datapackets or cells until the failure is isolated and repaired. Forexample, isolating a logical circuit failure requires that a technicianaccess a database to identify the logical connections which make up thelogical circuit. Once the logical connections are identified, theirstatus is ascertained and the logical circuit is repaired. The databaserecords, however, are manually entered and thus subject to human errorwhich, if present, increases circuit downtime until the logicalconnections making up the failed logical circuit are identified.Furthermore troubleshooting the physical circuit often requires takingthe network circuit out of service to perform testing, thus increasingthe downtime and loss of data in the network circuit.

It is with respect to these considerations and others that the presentinvention has been made.

SUMMARY

In accordance with the present invention, the above and other problemsare solved by methods for automatically identifying a logical circuitfailure in a data network. According to one method, a logical circuit inthe data network is periodically monitored for status informationpertinent to the logical circuit. The data network may be a frame relaynetwork or an asynchronous transfer mode (“ATM”) network. The logicalcircuit may include one more logical connections for communicating datain the data network. The logical circuit may be a permanent virtualcircuit (“PVC”) or a switched virtual circuit (“SVC”). A failure of thelogical circuit is then identified, based on the status information,without manual intervention.

The periodic monitoring of the logical circuit may include periodicallymonitoring one or more logical connections in the logical circuit. Theperiodic monitoring of the logical connections in the logical circuitmay include periodically requesting trap data for each logicalconnection. The trap data may include status information for eachlogical connection in the logical circuit. Identifying a failure of thelogical circuit may include analyzing the status information for theeach logical connection. If the status information for the at least onelogical connection indicates that a logical connection is no longercommunicating data, then determining that the logical connection hasfailed. After determining that the logical connection has failed,waiting a predetermined time period to determine whether the failedlogical connection has been restored. If after the predetermined timeperiod, the logical connection has not been restored, then determiningthat the logical circuit has failed.

The method may further include identifying a logical identifier for thelogical circuit and based on the logical identifier, accessing adatabase to identify each logical connection in the logical circuit. Thelogical identifier may be a data link connection identifier (“DLCI”) ora virtual path/virtual circuit identifier (“VPI/VCI”). Each logicalconnection may include a network-to-network interface.

In accordance with other aspects, the present invention relates to asystem for automatically identifying a logical circuit failure in a datanetwork. The system includes a network device for collecting trap datafor the logical circuit in the data network, a logical element module incommunication with the network device for receiving the trap data forthe logical circuit, and a network management module in communicationwith the logical element module. The network management module isutilized to periodically retrieving the trap data for the logicalcircuit and identify a failure of the logical circuit based on the trapdata, without manual intervention.

These and various other features as well as advantages will be apparentfrom a reading of the following detailed description and a review of theassociated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an illustrative data network according to anembodiment of the invention.

FIG. 2 illustrates a local access and transport area (“LATA”) and anetwork 20 management system which may be utilized to automaticallyidentify a failure in a logical circuit in the data network of FIG. 1,according to an embodiment of the invention.

FIG. 3 illustrates a flowchart describing logical operations forautomatically identifying a failure in a logical circuit in the datanetwork of FIG. 1, according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention provide for a method and systemautomatically identifying a failure in a logical circuit in a datanetwork. In the following detailed description, references are made tothe accompanying drawings that form a part hereof, and in which areshown by way of illustration specific embodiments or examples. Referringnow to the drawings, in which like numerals represent like elementsthrough the several figures, aspects of the present invention and theexemplary operating environment will be described.

Embodiments of the present invention may be generally employed in a datanetwork 2 as shown in FIG. 1. The data network 2 includes local accessand transport areas (“LATAs”) 5 and 15 which are connected by anInter-Exchange Carrier (“IEC”) 10. It should be understood that theLATAs 5 and 15 may be operated by a commonly owned Local ExchangeCarrier (“LEC”). It should be further understood that the IEC 10 mayinclude one or more data networks which may be operated by a commonlyowned IEC. It will be appreciated by those skilled in the art that thedata network 2 may be a frame relay network, asynchronous transfer mode(“ATM”) network, or any other network capable of communicating dataconforming to Layers 2-4 of the Open Systems Interconnection (“OSI”)model developed by the International Standards Organization,incorporated herein by reference. It will be appreciated that thesenetworks may include, but are not limited to, communications protocolsconforming to the Multiprotocol Label Switching Standard (“MPLS”)networks and the Transmission Control Protocol/Internet Protocol(“TCP/IP”), which are known to those skilled in the art.

The data network 2 includes a network circuit which channels databetween a host device 112 and a remote device 114 through the LATA 5,the IEC 10, and the LATA 15. It will be appreciated by those skilled inthe art that the host and remote devices 112 and 114 may be local areanetwork (“LAN”) routers, LAN bridges, hosts, front end processors, FrameRelay Access Devices (“FRADs”), or any other device with a frame relay,ATM, or network interface. It will be further appreciated that in thedata network 2, the LATAs 5 and 15 and the IEC 10 may include networkelements (not shown) which support interworking to enable communicationsbetween host and remote devices supporting dissimilar protocols. Networkelements in a data network supporting interworking may translate framerelay data packets or frames sent from a host FRAD to ATM data packetsor cells so that a host device may communicate with a remote devicehaving an ATM interface. The LATAs 5 and 15 and the IEC 10 may furtherinclude one or more interconnected network elements, such as switches(not shown), for transmitting data.

The network circuit between the host device 112 and the remote device114 in the data network 2 includes a physical circuit and a logicalcircuit. As used in the foregoing description and the appended claims, aphysical circuit is defined as the physical path that connects the endpoint of a network circuit to a network device. For example, thephysical circuit of the network circuit between the host device 112 andthe remote device 114 includes the physical connection 121 between thehost device 112 and the LATA 5, the physical connection 106 between theLATA 5 and the IEC 10, the physical connection 108 between the IEC 10and the LATA 15, and the physical connection 123 between the LATA 15 andthe remote device 114. Router and switches within the LATAs 5 and 15 andthe IEC 10 carry the physical signal between the host and remote enddevices 112 and 114 through the physical circuit.

It should be understood that the host and remote devices may beconnected to the physical circuit described above using user-to-networkinterfaces (“UNIs”). As is known to those skilled in the art, an UNI isthe physical demarcation point between a user device (e.g, a hostdevice) and a public data network. It will further be understood bythose skilled in the art that the physical connections 106 and 108 mayinclude trunk circuits for carrying the data between the LATAs 5 and 15and the IEC 10. It will be further understood by those skilled in theart that the connections 121 and 123 may be any of various physicalcommunications media for communicating data such as a 56 Kbps line or aT1 line carried over a four-wire shielded cable or over a fiber opticcable.

As used in the foregoing description and the appended claims, a logicalcircuit is defined as a portion of the network circuit wherein data issent over variable communication data paths or logical connectionsestablished between the first and last network devices in a LATA or IECnetwork and over fixed communication data paths or logical connectionsbetween LATAs (or between IECs). Thus, no matter what path the datatakes within each LATA or IEC, the beginning and end of each logicalconnection between networks will not change. For example, the logicalcircuit of the network circuit in the data network 2 may include avariable communication path within the LATA 5 and a fixed communicationpath (i.e., the logical connection 102) between the LATA 5 and the IEC10. It will be understood by those skilled in the art that the logicalconnections 102 and 104 in the data network 2 may includenetwork-to-network interfaces (“NNIs”) between the last sending switchin a LATA and the first receiving switch in an IEC.

As is known to those skilled in the art, each logical circuit in a datanetwork may be identified by a unique logical identifier. In frame relaynetworks, the logical identifier is called a Data Link ConnectionIdentifier (“DLCI”) while in A TM networks the logical identifier iscalled a Virtual Path Identifier/Virtual Circuit Identifier (“VPI/VCI”).In frame relay networks, the DLCI is a 10-bit address field contained inthe header of each data frame and contains identifying information forthe logical circuit as well as information relating to the destinationof the data in the frame and service parameters for handling networkcongestion. For example, in the data network 2 implemented as a framerelay network, the designation DLCI 100 may be used to identify thelogical circuit between the host device 112 and the remote device 114.It will be appreciated that in data networks in which logical circuitdata is communicated through more than one carrier (e.g., an LEC and anIEC) the DLCI designation for the logical circuit may change in aspecific carrier's network. For example, in the data network 2, thedesignation DLCI 100 may identify the logical circuit in the LATA 5 andLATA 15 but the designation DLCI 800 may identify the logical circuit inthe IEC 10.

Illustrative service parameters which may be included in the DLCIinclude a Committed Information Rate (“CIR”) parameter and a CommittedBurst Size (“Bc”) parameter. As is known to those skilled in the art,the CIR represents the average capacity of the logical circuit and theBc represents the maximum amount of data that may be transmitted. Itwill be appreciated that the logical circuit may be provisioned suchthat when the CIR or the Bc is exceeded, the receiving switch in thedata network will discard the frame. It should be understood that thelogical circuit parameters are not limited to CIR and Bc and that otherparameters known to those skilled in the art may also be provisioned,including, but not limited to, Burst Excess Size (“Be”) and CommittedRate Measurement Interval (“Tc”). In ATM networks, the VPI/VCI is anaddress field contained in the header of each ATM data cell and containsidentifying information for the logical circuit as well as informationspecifying a data cell's destination and specific bits which mayindicate, for example, the existence of congestion in the network and athreshold for discarding cells.

It should be understood that the logical circuit in the data network 2may be a permanent virtual circuit (“PVC”) available to the network atall times or a temporary or a switched virtual circuit (“SVC”) availableto the network only as long as data is being transmitted. It should beunderstood that the data network 2 may further include additionalswitches or other interconnected network elements (not shown) creatingmultiple paths within each LATA and IEC for defining each PVC or SVC inthe data network. It will be appreciated that the data communicated overthe logical connections 102 and 104 may be physically carried by thephysical connections 106 and 108.

The data network 2 may also include a failover network 17 for reroutinglogical circuit data, according to an embodiment of the invention. Thefailover network 17 may include a network failover circuit includingphysical connections 134 and 144 and logical connections 122 and 132 forrerouting logical circuit data in the event of a failure in the networkcircuit between the host device 112 and the remote device 114. The datanetwork 2 may also include a network management system 175 incommunication with the LATA 5 and the LATA 15 which may be utilized toobtain status information for the logical and physical circuit betweenthe host device 112 and the remote device 114. The network managementsystem 175 may also be utilized for rerouting logical data in the datanetwork 2 between the host device 112 and the remote device 114. Thenetwork management module 176 will be discussed in greater detail in thedescription of FIG. 2 below.

Turning now to FIG. 2, an illustrative data carrier (i.e., the LATA 5)and the network management system 175, contained in the data networkdescribed in FIG. 1 above, will now be described. As shown in FIG. 2,the LATA 5 includes interconnected network devices such as switches 186,187, and 188. It will be appreciated that the data network 2 may alsocontain other interconnected network devices and elements (not shown)such as digital access and cross connect switches (“DACS”), channelservice units (“CSUs”), and data service units (“DSUs”). As discussedabove in the description of FIG. 1, the connection data paths of alogical circuit within a data network may vary between the first andlast network devices in a data network. For example, as shown in FIG. 2,the logical circuit in the LATA 5 may include the communication path 185between the switches 186 and 188 or the communication path 184 betweenthe switches 186, 187, and 188. As discussed above, it should beunderstood that the actual path taken by data through the LATA 5 is notfixed and may vary from time to time, such as when automatic reroutingtakes place.

It will be appreciated that the switches 186, 187, and 188 may include asignaling mechanism for monitoring and signaling the status of thelogical circuit in the data network 2. Each time a change in the statusof the logical circuit is detected (e.g., a receiving switch beginsdropping frames), the switch generates an alarm or “trap” which may thenbe communicated to a management station, such as a logical elementmodule (described in detail below), in the network management system175. In one embodiment, the signaling mechanism may be in accord with aLocal Management Interface (“LMI”) specification, which provides for thesending and receiving of “status inquiries” between a data network and ahost or remote device. The LMI specification includes obtaining statusinformation through the use of special management frames (in frame relaynetworks) or cells (in ATM networks). In frame relay networks, forexample, the special management frames monitor the status of logicalconnections and provide information regarding the health of the network.In the data network 2, the host and remote devices 112 and 114 receivestatus information from the individual LATAs they are connected to inresponse to a status request sent in a special management frame or cell.The LMI status information may include, for example, whether or not thelogical circuit is congested or whether or not the network circuit hasfailed. It should be understood that the parameters and the signalingmechanism discussed above are optional and that other parameters andmechanisms may also be utilized to obtain connection status informationfor a network circuit.

As discussed above in, the LATA 5 may be connected to the networkmanagement system 175 which, as shown in FIG. 2, includes a serviceorder system 160, a network database 170, a logical element module 153,a physical element module 155, a network management module 176, and atest module 180. The service order system 160 is utilized in the datanetwork 2 for receiving service orders for provisioning networkcircuits. The service order includes information defining thetransmission characteristics (i.e., the logical circuit) of the networkcircuit. The service order also contains the access speed, CIR, burstrates, and excess burst rates. The service order system 160 communicatesthe service order information to a network database 170 over managementtrunk 172. The network database 170 assigns and stores the parametersfor the physical circuit for the network circuit such as a port numberon the switch 186 for transmitting data over the physical connection 121to and from the host device 112.

The network database 170 may also be in communication with an operationssupport system (not shown) for assigning physical equipment to thenetwork circuit and for maintaining an inventory of the physicalassignments for the network circuit. An illustrative operations supportsystem is “TIRKS” ® (Trunks Integrated Records Keeping System) marketedby TELECORDIA™ TECHNOLOGIES, Inc. of Morristown, N.J. The networkdatabase 170 may also be in communication with a Work ForceAdministration and Control system (“WFA/C”) (not shown) used to assignresources (i.e., technicians) to work on installing the physicalcircuit.

The network management system 175 also includes the logical elementmodule 153 which is in communication with the switches 186, 187, and 188through management trunks 185. The logical element module 153 runs anetwork management application program to monitor the operation oflogical circuits which includes receiving trap data generated by theswitches which indicate the status of logical connections. The trap datamay be stored in the logical element module 153 for later analysis andreview. The logical element module 153 is also in communication with thenetwork database 170 via management trunks 172 for accessing informationregarding logical circuits such as the logical identifier data. Thelogical identifier data may include, for example, the DLCI or VPI/VCIheader information for each data frame or cell in the logical circuitincluding the circuit's destination and service parameters. The logicalelement module 153 may consist of terminals (not shown) that display amap-based graphical user interface (“GUI”) of the logical connections inthe data network. An illustrative logical element module is theNAVISCORE™ system marketed by LUCENT TECHNOLOGIES, Inc. of Murray Hill,N.J.

The network management system 175 further includes the physical elementmodule 155 in communication with the physical connections of the networkcircuit via management trunks (not shown). The physical element module155 runs a network management application program to monitor theoperation and retrieve data regarding the operation of the physicalcircuit. The physical element module 155 is also in communication withthe network database 170 via management trunks 172 for accessinginformation regarding physical circuits, such as line speed. Similar tothe logical element module 153, the physical logical element module 155may also consist of terminals (not shown) that display a map-based GUIof the physical connections in the LATA 5. An illustrative physicalelement module is the Integrated Testing and Analysis System (“INTAS”),marketed by TELECORDIA™ TECHNOLOGIES, Inc. of Morristown, N.J., whichprovides flow-through testing and analysis of telephony services.

The physical element module 155 troubleshoots the physical connectionsfor the physical circuit by communicating with test module 180, whichinterfaces with the physical connections via test access point 156. Thetest module 180 obtains the status of the physical circuit bytransmitting “clean” test signals to test access point 156 which“loopback” the signals for detection by the test module 180. It shouldbe understood that there may be multiple test access points on each ofthe physical connections for the physical circuit.

The network management system 175 further includes the networkmanagement module 176 which is in communication with the service ordersystem 160, the network database 170, the logical element module 153,and the physical element module 155 through communications channels 172.The communications channels 172 may be on a LAN. The network managementmodule 176 may consist of terminals (not shown), which may be part of ageneral-purpose computer system that displays a map-based GUI of thelogical connections in data networks. The network management module 176may communicate with the logical element module 153 and the physicalelement module 155 using a Common Object Request Broker Architecture(“CORBA”). As is known to those skilled in the art, CORBA is an open,vendor-independent architecture and infrastructure which allowsdifferent computer applications to work together over one or morenetworks using a basic set of commands and responses. The networkmanagement module 176 may also serve as an interface for implementinglogical operations to provision and maintain network circuits. Thelogical operations may be implemented as machine instructions storedlocally or as instructions retrieved from the element modules 153 and155. An illustrative method detailing the provisioning and maintenanceof network circuits in a data network is presented in U.S. patentapplication Ser. No. 10/348,592, entitled “Method And System ForProvisioning And Maintaining A Circuit In A Data Network,” filed on Jan.23, 2003, and assigned to the same assignee as this application, whichis expressly incorporated herein by reference. An illustrative networkmanagement module is the Broadband Network Management System® (“BBNMS”)marketed by TELECORDIA™ TECHNOLOGIES, Inc. of Morristown, N.J.

It should be understood that in one embodiment, the network managementsystem 175 may also be in communication with the LATA 15, the IEC 10,and the failover network 17.

FIG. 3 illustrates a flowchart describing logical operations 300 forautomatically identifying a failure in a logical circuit in the datanetwork 2 of FIG. 1, according to an embodiment of the invention. Thelogical operations 300 begin at operation 305 where the networkmanagement module 176 communicates with the logical element module 153to request trap data indicating the status of a logical connectionmaking up the logical circuit in the data network 2. It should beunderstood that although the trap data is continuously generated by theswitches in the data network 2 and then communicated to the logicalelement module 153 each time a change in status occurs, in thisembodiment, the network management module 176 may be configured so thatthe trap data is only requested periodically (e.g., once every hour) sothat system resources are conserved. It will be appreciated that inanother embodiment of the invention, the trap data could be processedpassively from the switches by the logical element module 153 (where thetrap data is stored). The network management module 176, incommunication with the logical element module 153, may then beconfigured to actively poll only those switches carrying logicalcircuits indicating trouble (e.g., dropped frames or cells) to furtherconserve system resources. Once the request for trap data is made, allof the trap data collected in the last time period (e.g., one hour) iscommunicated to the network management module 176 from the logicalelement module 153.

For example, in one embodiment, the network management module 176 may beconfigured to check the status of the NNI or logical connection 102 inthe data network 2 by requesting the trap data generated by the switches186, 187, and 188 in the LATA 5. It will be appreciated that in oneembodiment, the network management module 176 may be configured to firstrequest trap data for a logical connection on one end of a logicalcircuit (e.g., the host end) and then identify the logical connectionfor the other end of the logical circuit (e.g., the remote end) based onthe logical identifier (i.e., the DLCI or VPI/VCI information) for thelogical circuit. It will be appreciated that the network managementmodule 176 may obtain the logical identifier by polling the logicalelement module 153. Once the logical identifier for the logical circuithas been obtained, the network management module 176 may then access thenetwork database 170 to “lookup” the NNI or logical connection on thefar end of the logical circuit and request the trap data for thatlogical connection.

After requesting trap data for a logical connection (or logicalconnections) in the data network 2 at operation 305, the logicaloperations 300 continue at operation 310 where the network managementmodule 176 analyzes the received trap data and identifies a logicalconnection failure at operation 315. As discussed above in thedescription of FIG. 2, trap data indicating a logical connection failuremay include status information indicating that a switch in the datanetwork is discarding frames or cells. Such an event may occur, forexample, when the maximum CIR or Bc (as specified in the DLCI of a framein a frame relay network, for example) is exceeded. If at operation 315,it is determined that a logical connection failure has not occurred, thelogical operations 300 then return to operation 305 where the networkmanagement module 176 again requests trap data from the logical elementmodule 153 during the next predetermined period (e.g., the beginning ofthe next hour). If, however, at operation 315 it is determined that alogical connection failure has occurred, the logical operations continuefrom operation 315 to operation 320 where the network management module176 waits a predetermined period (e.g., five minutes) to determinewhether the failed logical connection has been restored (i.e., thecommunication of data over the logical connection has resumed). Forexample, in the data network 2 illustrated in FIG. 2, the “X” markingthe logical connections 102 and 104 indicates that the logicalconnection is “down beyond” (i.e., not communicating data) the NNIs forthe logical circuit in the LATAs 5 and 15.

If at operation 320, the network management module 176 determines thatthe failed logical connection has been restored, the logical operations300 return to operation 305 where the network management module 176again requests trap data from the logical element module 153 during thenext predetermined period. If, however, at operation 320 the networkmanagement module 176 determines that the failed logical connection hasnot been restored during the predetermined wait period, the logicaloperations 300 continue to operation 325 where the network managementmodule 176 indicates that the logical circuit has failed.

Once the network management module 176 has indicated a logical circuitfailure it may initiate an automatic reroute procedure using thefailover network 17. An illustrative method detailing rerouting logicalcircuit data over a failover network is presented in U.S. patentapplication Ser. No. 10/744,921, entitled “Method And System ForAutomatically Rerouting Logical Circuit Data In A Data Network,” filedon Dec. 23, 2003, and assigned to the same assignee as this application,which is expressly incorporated herein by reference.

It will be appreciated that the embodiments of the invention describedabove provide for a method and system for automatically identifying afailure in a logical circuit in a data network. The various embodimentsdescribed above are provided by way of illustration only and should notbe construed to limit the invention. Those skilled in the art willreadily recognize various modifications and changes that may be made tothe present invention without following the example embodiments andapplications illustrated and described herein, and without departingfrom the true spirit and scope of the present invention, which is setforth in the following claims.

What is claimed is:
 1. A method to identify a failure in a logicalcircuit, the method comprising: receiving non-requested trap data from aplurality of switches forming a logical circuit, the logical circuitspanning first, second, and third logical networks; polling first andsecond switches of the logical circuit exclusive of others of theplurality of switches of the logical circuit, the first switch forming afirst network-to-network interface between the first logical network andthe second logical network, the second switch forming a secondnetwork-to-network interface between the second logical network and thethird logical network, the first logical network being in a first localaccess and transport area, the second logical network being aninter-exchange carrier network, the third logical network being in asecond local access and transport area, and the first and secondswitches selected for polling based on the trap data indicating aproblem at the first and second switches; and identifying a failure ofthe logical circuit without manual intervention based on the polling. 2.The method of claim 1, wherein polling the first and second switchescomprises performing the polling via a network management moduleseparate from the switches forming the logical circuit.
 3. The method ofclaim 1, wherein polling the first and second switches comprisesperiodically requesting second trap data from the first and secondswitches.
 4. The method of claim 3, wherein identifying the failure ofthe logical circuit comprises: when the second trap data indicates thatthe at least one of the first or second network-to-network interfaces isno longer communicating data, then determining that the at least one ofthe first or second network-to-network interfaces has failed; afterdetermining that the at least one of the first or secondnetwork-to-network interfaces has failed, waiting a predetermined timeperiod to determine whether the at least one of the first or secondnetwork-to-network interfaces is restored; and when after thepredetermined time period, the at least one of the first or secondnetwork-to-network interfaces is not restored, indicating that thelogical circuit has failed.
 5. The method of claim 1 further comprising:identifying a logical identifier for the logical circuit; and based onthe logical identifier, accessing a database to identify a first logicalconnection associated with the first network-to-network interface and asecond logical connection associated with the second network-to-networkinterface.
 6. The method of claim 5, wherein the logical identifier is adata link connection identifier (DLCI).
 7. The method of claim 5,wherein the logical identifier is a virtual path/virtual circuitidentifier (VPI/VCI).
 8. The method of claim 1, wherein the logicalcircuit is a permanent virtual circuit.
 9. The method of claim 1,wherein the logical circuit is a switched virtual circuit.
 10. Anapparatus to automatically identify a logical circuit failure, theapparatus comprising: a memory comprising machine readable instructions;and a processor to execute the instructions to perform operationscomprising: analyzing non-requested trap data received from a pluralityof switches forming a logical circuit, the logical circuit spanningfirst, second, and third logical networks; polling first and secondswitches of the logical circuit exclusive of others of the plurality ofswitches of the logical circuit, the first switch forming a firstnetwork-to-network interface between the first logical network and thesecond logical network, the second switch forming a secondnetwork-to-network interface between the second logical network and thethird logical network, the first logical network being in a first localaccess and transport area, the second logical network being aninter-exchange carrier network, the third logical network being in asecond local access and transport area, and the first and secondswitches selected for polling based on the trap data indicating aproblem at the first and second switches; and identifying a failure ofthe logical circuit without manual intervention based on the polling.11. The apparatus of claim 10, wherein the memory and the processor arelocated in a network management module separate from the switchesforming the logical circuit.
 12. The apparatus of claim 10, wherein theprocessor is to poll the first and second switches by periodicallyrequesting second trap data from the first and second switches.
 13. Theapparatus of claim 12, wherein the processor is to identify the failureof the logical circuit by: when the second trap data indicates that thefirst network-to-network interface is no longer communicating data,determining that the first network-to-network interface has failed;after determining that the first network-to-network interface hasfailed, waiting a predetermined time period to determine whether thefirst network-to-network interface is restored; and when after thepredetermined time period, the first network-to-network interface is notrestored, indicating that the logical circuit has failed.
 14. Theapparatus of claim 10, wherein the processor is to: identify a logicalidentifier for the logical circuit; and based on the logical identifier,access a database to identify a first logical connection associated withthe first network-to-network interface and a second logical connectionassociated with the second network-to-network interface.
 15. Theapparatus of claim 14, wherein the logical identifier is a data linkconnection identifier (DLCI) or a virtual path/virtual circuitidentifier (VPI/VCI).
 16. A machine accessible storage device comprisinginstructions that, when executed, cause a machine to execute a methodcomprising: analyzing non-requested trap data received from a pluralityof switches forming a logical circuit, the logical circuit spanningfirst, second, and third logical networks; polling first and secondswitches of the logical circuit exclusive of others of the plurality ofswitches of the logical circuit, the first switch forming a firstnetwork-to-network interface between the first logical network and thesecond logical network, the second switch forming a secondnetwork-to-network interface between the second logical network and thethird logical network, the first logical network being in a first localaccess and transport area, the second logical network being aninter-exchange carrier network, the third logical network being in asecond local access and transport area, and the first and secondswitches selected for polling based on the trap data indicating aproblem at the first and second switches; and identifying a failure ofthe logical circuit without manual intervention based on the polling.17. The machine accessible storage device of claim 16, wherein pollingthe first and second switches comprises performing the polling via anetwork management module separate from the switches forming the logicalcircuit.
 18. The machine accessible storage device of claim 16, whereinpolling the first and second switches comprises periodically requestingsecond trap data from the first and second switches.
 19. The machineaccessible storage device of claim 16, wherein identifying the failureof the logical circuit comprises: when the second trap data indicatesthat the at least one of the first or second network-to-networkinterfaces is no longer communicating data, then determining that the atleast one of the first or second network-to-network interfaces hasfailed; after determining that the at least one of the first or secondnetwork-to-network interfaces has failed, waiting a predetermined timeperiod to determine whether the at least one of the first or secondnetwork-to-network interfaces is restored; and when after thepredetermined time period, the at least one of the first or secondnetwork-to-network interfaces is not restored, indicating that thelogical circuit has failed.
 20. The machine accessible storage device ofclaim 16, wherein the instructions are further to cause the machine toinitiate a reroute procedure to reroute data from the logical circuit toa failover circuit in response to identifying the failure of the logicalcircuit to bypass the first and second network-to-network interfaces andthe second logical circuit.